I am going to get portig (probably trenga) and I want to bore it over some and I was thinking about .40 over what do youy guys think??? Then I am going to get a 30mm carb and an lrd pipe. Is this a good set up for the dunes?

 

Oooo come on some one has to think this is a good choice or a bad one. Or at least opion.

 

well, the only purpose of a small overbore like a .40 over is to get a clean cylinder wall surface. These smaller overbores do not in themselves give power gains. Any power gain felt from one will simply be from getting a clean cylinder wall surface and restoring lost compression. Generally you don't want to do an overbore any larger than is absolutely required to get a good clean surface, and for several reasons.

1. You can only overbore your cylinder so many times before you need to get it re-sleeved. Smaller overbores mean the original sleeve will last longer, and rebuilds will cost less

2. The thinner the sleeve gets from boring it out, the more likely it will be for your engine to have cooling problems and other reliability issues from thinner cylinder walls.

The best thing to do is just let a shop figure out how much it needs to be bored (with an 04 it may be in good enough shape that it won't need bored out at all)

You will have to go to a big bore kit like vito's 240 to get any noticable gains out of boring out your cylinder. I think a .40 over will give you something ridiculously small like 2-4 cc's over what you already have. It's just not enough to make a difference you could ever notice.

 

Okay I will just get it ported and polished. Thanks